Voltage regulation



i4, 1947. J. A. PQTTER 2,414,242

v l VOLTAGE REGULATI'ON Filed July 14,:1944

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r AA JA A ATTORNE/ Patented Jan. 14,1947

UNITED STATES Immun"4 orrlcevoL'rAGr-J REGULATION `lames A. Potter, Long Valley,

Bell Telephone Laboratories,

N. J., assigner to Incorporated,

New York, N. `Y., a corporation of New York Application July 14, 1944, Serial No. 544,886

l This invention .relates to voltage regulation and particularly to apparatus for regulating the direct current supplied to a load to maintain the load voltage substantially constant at a desired value. A

An object of the invention is to provide improved regulated rectifying apparatus for supplying direct current to a load.

There has been used heretofore regulated rectifying apparatus employing a space discharge rectifying device-upon the control grid-cathode circuit o f which is impressed a control voltage for controlling the amplitude of the rectified curgrid-cathode voltage applied to the series space discharge device may be obtained from the output of an electronic amplier upon the input of which a control voltage is impressed. The control voltage of such arrangements may have a plurality of components. There may be used, for example, two component voltages, one being a direct voltage proportional to the load voltage and the other being a substantially constant voltage in opposed relationship to the ilrst. The resultant voltage is therefore a direct voltage of small amplitude and having variations corresponding to load voltage changes, the magnitude of this voltage being suitable for application to the grid-cathode circuit of an electronic ampliller or of a grid controlled rectifying device. It has been the'practice, in order to avoid the necessity of using batteries, to derive the constant voltage component, or the so-called 'reference standard voltage, from a circuit comprising a cold cathode, gas-filled voltage stabilizing tube energized from the rectified response to current changes therethrough so as to maintain substantially constant the voltage drop across the tube.

In designing the regulated rectiflers shown and described herein, the diiliculty was encountered that'the voltage across the load is less than the breakdown voltagev of the voltage stabilizing, cold cathode tube used for supplying the reference standard voltage. There was encountered the further problem of obtaining a -suillciently voltage source and having the property of changing its resistance ln 11 Claims. (Cl. 171-312) A high voltage in the anode-cathode circuit of an amplier tube to cause the anode-cathode resistance of the regulator tube which is controlled from theamplifier output to' vary over a wide range in response to load voltage changes, for example. These and other problems have been solved in accordance with the present invention.-

In accordance with a specific embodimenty of the invention shown and described herein for the purpose of illustration, there are provided a plurallty of regulated rectiers for simultaneously supplying current to different loads respectively and for maintaining substantially constant at desired Values the voltages across said loads respectively. Each regulated rectifier is of the type employing a series regulator tube the resistance of which is varied under control of the output voltage of an electronic amplier. .The

vcontrol voltage impressed upon the input control grid-cathode circuit o f the amplifier has three component unidirectional voltages, a rst component varying with load voltage changes, a second component being a substantially constant reference standard voltage having a polarity which is in opposition to the Aiirst component voltage, and a third component which varies with load current. The iirst and third component voltages have such polarities, respectively, that when the resistance of the load is fixed, a change in load-voltage due to a line voltage change, for

example, causes the voltage changes of the iirst and third components to be in opposition but the changes of the rst voltage component are predominantly large. However, when the load resistance is changed, the resulting voltage changes of the rst and third components are in aiding relationship in the controll grid-cathode circuit of the amplifier tube. The second component voltage is derived by means of a voltage stabilizing device to which is applied a voltage larger than the output voltage of the rectifier which supplies current to the load, the additional voltage required being supplied by an auxiliary rectifying apparatus.

ing is a schematic view of regulated rectifying apparatus embodying the invention. i

Referring to the drawing, there are provided three regulated rectiliers each for supplying direct current to a load and for maintaining each The single ligure of the accompanying draw- 1 tial oi one terminal of f grounded which is 60 volts negative other terminal which is grounded. A second regulated rectier comprising a full wave rectifier tube 26, a triple grid ampiier tube'21, and a beam power series regulator tube 28 supplies polarity of one terminal of which is 36 volts negative with respect to its other terminal which is grounded. The third regulated rectifier, comprising a full wave rectier tube 5I, a triple grid ampliertube 52, and a beam power series regulator tube 53, supplies direct current to a load 54 the polarity of one terminal of which is 24 volts negative with respect to its other terminal which is grounded.

There is also provided an auxiliary rectifier made up of varistors 16 connected in a bridge circuit two opposed vertices of which are connected through a Z700-ohm resistor 11 to the terminals oi secondary'winding 18 of a transformer the primary winding 19 of which is connected to a 110- volt alternating current supply source 86. .The conjugate vertices of the bridge rectifier 16 are connected to the input terminals of a ripple lter with respect to its I comprising a series reactance coil 8| and shunt condensers 82. The lead 83 connected to the positive output terminal of the filter 8l, 82 is directly connected to the G0-volt terminal of the load I3. The voltage across the output terminals ofiilter 8l, 82 is about 92 volts so that the lead 84 connected to the negative filter terminal is 152 volts negative with respect to ground. Lead 85 is conv nected through a Z700-ohm resistor 81 to the negative terminal of iilter 8l, 82, the operating voltage drop across resistor 81 being such that the potential of lead 85 is 105 volts negative with respect to ground. Y

Considering further the 6G-volt regulated rectifier, the two anodes of rectifier tube I0 are connected respectively to the Iend terminals of the secondary winding of a transformer I4 the primary winding of which is connected to the supply source 80. The rectifier output terminals going to a mid-tap of the secondary winding oi transformer I4 and to the cathode of rectifier tube Ill respectively are connected to the input direct current to a load 28 the A potential dividing circuit is connected across the f terminals of voltage stabilizingtube 2l, said circuit comprising 62,000-ohm resistor 22, 0.1-megohm potentiometer 23, and 500-ohm resistor 24 in series. One terminal of a, 10,0ii0-ohm resistor V25 is connected to the negative output terminal of iilter I5, I6 and the other terminal of resistor 25 is connected to the common terminal of potentiometei` .23 and resistor 24. The two-electrode, gas-filled tube 90 in avpath connecting the anode and cathode of tube II is provided to prevent the load voltage from risingto an excessive value. If the tube il'should fail to pass space current through resistor I9 and as a result Ycause zero grid-cathode voltage to be applied to tube I2, the load voltage would be increased to an excessivevalue. However, when the load Voltage is increased to 110 volts, tube 90 breaks down to cause current to flow through resistor is, thereby applying a negative bias to the grid of tube I2 i `to limit the load current and voltage. y

Considering the operation of the G0-volt regulated rectiiier, it will be noted that there are three component voltages in a series circuit connecting the control grid and cathode of amplier tube II. One of the kcomponents is the voltage drop of about 13 volts across the load compounding resistor l1, this voltage varying with load current. A second component is the voltage drop of about 67 volts across resistor 25, this voltage varying with load voltage. The third component isa portion of the substantially constant voltage across voltage stabilizing tube 2l, that isythe terminals of a r1ppie lter comprising series reactance coils I5 and shunt condensers I6. The negative output terminal of the filter is connected through a series load compounding resistor I1 of 160 ohms to the negative terminal of load I3. The positive filteroutput terminal is connected through the space current'or anode-cathode path of the series regulator tube I2 to the grounded positive load terminal. The anode and screen grid of tube I2 are connected through a 30-ohm resistor I8. The cathode of amplifier tube II is connected to the negative load terminal and the anode of the tube is connected through 0.5-megohm resistor I9 to ground. The screen grid of tube II is given a potential of 24 volts positive voltage drop of about volts across the portion of 'potentiometer l23 between the common terminal of the potentiometer and resistor 24 and the variable potentiometer connection goingfto the control grid of tube II. The voltage drop across resistor I1 and the voltage drop across the portion of potentiometer 23 in the circuit are aiding with respect to each other and opposed to the voltage drop across resistor 25 so that the resultant potential of the control grid with respect to the cathode is about one volt negative. When an increase in load voltage occurs, due to a voltage increase of source 80, for. example, the resistance of the load being fixed, the voltage drop across resistor I1 and that across resistor 25 each increases, the increase of voltage across resistor 25 being larger. As a result the control grid becomes relatively more positive or less negative with respect to the cathode to. cause the space' current of tube II. flowing through resistor I9 to increase. Therefore the'controlgrid of regulator with respect to the cathode by connecting it to tential of -105 volts with respect to ground. .A

tube I2 becomes relatively more nega-tive with respect to its cathode to cause the anode-cathode resistance of the tube to increase and thus reduce the current flowing through load I 3 to restore the load voltage to its normal operating value. When the resistance of the load is reduced, for example, the loadvcurrent increases and the load voltage decreases'.l As a result the voltage drop across resistor I1 increases While` that across resistor 25 decreases. The voltage drops across resistors l1 and 25 being in opposition, the increase of voltyage `drop across resistor I1 and the decrease of voltage drop across resistor 25 cause the grid 0f tube II to become relatively .more negative with respect to the cathode by an amount equal to the sum of the two voltage changes. The `control grid l of regulator tube I2 thus becomes less negative with respect to the cathode to cause the load voltage to increase to its normal value, '.Ihe load voltage may be brought to a desired normal value by adjusting the variable contact of potentiom- 5 eter 23 to change the reference standard voltage component in the grid-cathode circuit of amplifier tube Considering the 3S-volt regulated rectifier, the two anodes of rectifier tube 26 are connected respectively to the end terminals of the secondary winding of a transformer 30, the primary winding of which is connected to the supply source 30. The rectifier output terminals going toa mid-tap of the secondary winding of transformer 30 and to the cathode of rectifier tube 26, respectively, are connected to the input terminals of a, ripple filter comprising series reactance coils 3| and shunt condensers 32. The negative output terminal of the filter is connected through a series load compounding resistor 33 of 86 ohms to the negative terminal of load 29. The positive filter output terminal is connected through the space current path of the series regulator' tube 28 to the grounded positive load terminal. The anode and screen grid of tube 28 are connected through a 30ohm resistor 34. Resistor 35 of 7,500 ohms and resistor 36 of 0.1 megohm are in a path connecting the lead 85 and the negative output terminal of filter 3|, 32, the common terminal of resistors 35 and 36 being connected to the control grid of amplifier tube 21. A 2,700- ohm resistor 31 and a cold cathode voltage stabilizing tube 38fln series are in a path connecting lead 84 to the negative load terminal. Across the cold cathode tube 38 are connected in series a 5,000-ohm potentiometer 39 and an 18,000-ohm resistor 40, the cathode of tube 21 being connected to the adjustable contact of potentiometer 39. The anode of tube 21 is connected through a 0.5-megohm resistor 4| to ground. A 1,500-ohm resistor 42 or so-called dummy load is connected across the load 28. The potential of the screen grid of tube 21 is made 40 volts positive with respect t'o the tube cathode by connecting it to namely, the voltage drop across resistor 36 havingn variations corresponding to load voltage changes. the voltage drop across the load compounding resistor 33 which varies with load current and the substantially constant reference standard voltage across resistor 40 and a portion of resistor 39 in series, the voltage drops'across resistors 36 and 33 being in aiding relationship and the voltage drop across the resistor 40 and a portion of resistor 39 being opposed to the voltage drops across resistors 36 and 33 to give a suitable operating control grid-cathode voltage for tube 21.

If the load voltage rises due to an increase of line voltage, for example, the voltage drop across resistor'33 increases while that across resistor 36 decreases and, since the latter voltage change is much larger than that across resistor 33, the grid of tube 21 is made relatively more positive or less negative with respect to the cathode and,

as a result, the voltage drop across resistor 4| is increased due to the increased space current of tube 21. Therefore, the control grid of regulator tube 28 becomes relatively more negative with respect to its cathode to cause the load current and voltage to be reduced. -If the load is increased, that is, the load resistance is decreased, while the line voltage is xed, the voltage drop across resistor 33 is increased and the voltage drop across resistor 36 is increased due to a decrease in load voltage, The control grid of tube 21 is therefore made relatively more negative with respect to its cathode to decrease the space current of the tube and to make the control grid of tube 28 relatively less negative with respect -to its cathode, thus reducing the resistance of the the lead 83. The anode of amplifier tube f1 is connected to the control grid of regulator tube 28.

The amplifierv tube 21, in order to provide voltage changes ofV suliicient magnitude across resistor 4| for controlling the regulator tube 28 to vary its anode-cathode resistance over a sufficiently large range, requires a larger voltage than the 36volt regulated load voltage in its anodecathode circuit. Therefore a voltage equal to the sum of the load voltage and the major poi'- tion of the substantially constant voltage across the voltage stabilizing tube 38 is impressed upon the anode-cathode circuit of tube 21, this voltage being about 100 volts. The resistors 35, 35 and 33 and the load 29 are in series path connecting the -105-volt lead 85 to ground. The voltage drop across resistor 35 is about 3 volts so that the control grid potential of tube 21 is about -102 volts with respect to ground or T2 volts with respect to the cathode since the cathode potential with respect to ground is about -100 volts. The voltage drop across load compounding resistor 33 -is also small, it being about 2 volts. Therefore, since the potential of lead 85 remains substantially constant at -105 volts with respect to ground due to the action of the voltage stabilizing tube 2|, the voltage across resistor 36 varies in response to load voltage changes, the'voltage drop across resistor 36 increasing in response to a decrease in load voltage and decreasing in response to a rise in load voltage. The voltage in the control grid-cathode path of tube 21 thus has three components,

anode-cathode path of tube 28. Increased load current is thus caused to flow to restore the load voltage to its normal value. The load voltage may be set at a. desired normal value by adjusting the movable contact of potentiometer 39 to change the potential of the cathode of tube 21 with respect to ground, that is, by changing the reerence standard voltage.

The 24volt regulated rectifier is somewhat like the 3G-volt regulated rectifier. The two anodes of the full Wave rectifier .tube 5| are connected `to the end terminals of the secondary winding of transformer the primary winding of which is supplied with alternating current from source 80. The rectifier output terminals are connected to the input of a filter comprising series reactance coils 56 and shunt condensers 51. The negative output .terminal of the filter is connected through a series load compounding rcsistor 58 of 43 ohms to-the negative terminal of load 54. The positive filter output terminal is connected through the space current path of regulator tube 53 -to 'the grounded positive load terminal. 'I'he anode and screen grid of tube 53 are connected through a 30-ohm resistor 59. Potentiometer 60 of 0.1 megohm and resistor 6| of 0.3 megohm are in a path connecting the lead and the negative output Iterminal of filter 56, 51. The adjustable contact of potentiometer 60 is connected to the control grid of tube 52 and its setting may be changed Ito adjust the load voltage to a desired value. A 3,900-ohm resistor 62 and cold cathode, vgas-filled voltage stabilizing tube 63 in series are in a. path connecting lead 84 to the negative loadterminal; the cathode of tube 52 being connected to the common terminal of resistor 62 and cold cathode .tube 63. The anode current path of tube 32 is completed through' 0.5-

megohm resistor 64 connecting the anode of tube 52 to ground. A dummy load resistor 65 of 1,500 ohms is connected across the load 56,

In this regulated rectifier, the voltage impressed upon the anode-cathode path of tube 52 is the sum of the substantially constant voltage across voltage stabilizing tube t3 and the load voltage, making the potential at the cathodeabout -99 volts Wi-th respect to ground, The control grid of tube 52. is aboutv 101 volts negative with respect to ground and tius at a suitable operating potentialiof about -2 volts with respect to thecathode. The component voltages in the gridcathode circuit of tube 52 are the voltage drop across resistor 6I and a portion of resistor 60 which varies in response to load yvoltage changes,

the voltage drop across resistor 58 which varies in accordance with load current changes and the substantially constant voltage drop across the voltage stabilizing tube 53. The voltage across tube 53 is opposed to each of the other two component voltages.

When an increasein load voltage occurs, the voltage 'across resistor BI and a. portion of potentiometer 60 is reduced to make the control grid of tube 52 relatively less negative. The control grid of tube 53 is thus-made more negative relative to its cathode to cause the load voltage to be restored to its normal operated value. An increase in load causes the voltage drop across resistor 58 to increase making the grid of tube 52 relatively more negative with respect to its cathode and the grid of tube 53 relatively less negative with respect to its cathode, thus causing the load voltage to be increased to its normal operating value.

What'is claimed is:

l. Means for regulating the voltage across a load to which is supplied. current from a direct current source comprising space discharge meansA having an anode, a cathode and a control elec trcde, auxiliary rectifying means for producing 2an output voltage, voltage stabilizing means the resistance of which changes in response to current changes therethrough at a rate to maintain substantially constant the voltage across said stabilizing means, a current path connected across said load comprising in series a resistor, said auxiliary rectifier and said voltage stabilizing means, the voltage of said direct current source and the voltage ci` said auxiliary rectifying means being in aiding relationship in said path so that the voltage across said voltage stabilizing means is greater than the voltage across said load and greater than the output voltage of said auxiliary rectifying means, and means for controlling the potential of said control electrode with respect to said cathode for causing load voltage changes to be minimized, said last-mentioned means comprising a circuit connecting said control electrode and cathode including a voltage which varies in response to load voltage changes and in opposition thereto a portion at least of the voltage across said voltage stabilizing means.

2. Means for regulating the voltage across a load to` Whichis supplied current from a direct current source comprising a space discharge means having an anode, a cathode and a control electrode, auxiliary rectifying meansfor producing an output voltage, voltage stabilizing means the resistance of which changes in response to current changes therethrough at a, rate to maintain substantially constant the voltage across said iiiary rechner and' said voltage stabilizing mesma the voltage of saiddirect current source and the voltage of said vauxiliary rectifying means being in aiding relationship in said path so lthat the voltage across said voltage stabilizing means is greater than the voltage across said load and greater than the output voltage of said auxiliary rectifying means, voltage dividing resistance means connected across said voltage stabilizing means and means for controlling the potential of said control electrode with respect to said cathode for causing load voltage changes to beminimized, said lastmentioned means comprising a circuit connecting said control electrode and cathode and including a voltage proportional to the load voltage and in opposition thereto a por- -tion of the voltage across said voltage dividing means. i

3. Means for regulating the voltage across a load to which is supplied current from a direct current source comprising space discharge means Vhaving an anode, a cathode and a control electrode, auxiliary rectifying means-for producing an output voltage, voltage stabilizing means the resistance of which changes in response to current changes therethrough at a rate to maintain substantially constant the voltage -across said stabilizing means, a, current path connected across' said load comprising in series a resistor, said auxiliaryrectiier and said voltage stabilizing means, the voltage oi said direct current source and the voltage of said auxiliary rectifying means being in aiding relationship in said path so that the voltage across said voltage stabilizing means is greater than .the voltage across said load and greaterthan the output voltage of said auxiliary rectifying means, means for connecting said cathode to one of said load terminals, means for connecting said anode to the other load terminal and a circuit connecting said cathode and said control electrode having therein the voltage across said load and in opposition to said load voltage at least a portion of the voltage across said voltage stabilizing means.

4. Means for regulating the voltage across a charge device having an anode, a cathode andv a controlelectrode and having its space current path in series with said load with respect to said direct current source, a load compounding resistor in series with said load with respect `to said direct current source, a first current path connected across said load including the space current path of an amplier space discharge .device having an anode, a cathode and a control electrode, a second current path connected across said load comprising in seriesan auxiliary rectiiler, a resistor and a voltage stabilizing device Ithe resistance of which changes in response to current changes therethrough at a rate to maintain substantially constant the vol-tage across said stabilizing device, a circuit connecting the cathode and control electrode of said amplier space discharge device having therein in series a rst volt' age component which varies with the voltage drop changes 'of said ampliiier space discharge device.

5. A combination in accordance with claim 4 in which the polarity of said second component voltage is in opposition to the polarity of said third component voltage.

6. A combination in accordance with-claim 4 in which the polarity of said second component voltage is in opposition to the polarity of said first and third component voltages.

7.v A combination in accordance with claim 4 in which the cathode of said amplifier space discharge device is connected to the negative load terminal through a path comprising said voltage stabilizing device.

8. Means for regulating the voltage across a load to which is supplied rectified alternating current from a source comprising electronic means having an input control grid-cathode circuit upon which a control voltage is impressed and Whichload current ows for causing the ampli- .tude of said load current to be controlled in response tovariations of said control voltage, auxiliary rectifying means for producing an output voltage, voltage stabilizing of which varies in response to current changes therethrough at a rate to cause the voltage across said voltage stabilizing means to remain substantially constant and a current path connected in shunt with said load with respect to said source comprising yin series the output of' said auxiliary rectifier. said voltage stabilizing means and a resistor. the VVoutput voltage of said auxiliary rectifier being in` aiding relationship to the `load voltmeans the resistance an output anode-cathode circuit through load voltage changes, a circuit connecting the control grid and cathode of said amplifier space discharge device comprising said rst voltage stabilizing device and at least a portion of said resistance means, the polarity of the voltage across said first voltage stabilizing means being in opposition to the voltage across said resistance means in said circuit, and means for impressing upon the control grid-cathode path of said regulator space discharge device a voltage derived from the anode-cathode path of said amplifier space discharge device for causing the load current to be controlled to maintain said load voltv age substantially constant.

' circuit connected to the control electrode-cathage so that the sum of the voltage drop across said voltage stabilizing means and the voltage drop across said resistor is greater th-an said load voltage, said input control grid-cathode circuit including` said resistor for causing load voltage variations to be impressed upon said control gridlcathode circuit, thereby controlling the load current to minimize saidA load voltage variations 9. Means for regulating the voltage across a load to which is supplied current from a direct current source comprising a series regulator space discharge device having an anode, a cathode and a control electrode, the anode-cathode discharge path of which is in series with spect to said direct current source, an ampliiier space discharge device having an anode, a cathode and a control electrode, avoltage stabilizing device the resistance of which changes in response to change of current therethrough lto maintain the voltage across said device substantially constant. a circuit comprising auxiliary rectifyingmeans for supplying direct current to said voltage stabilizing device, a space current circuit connecting the anode and cathode of said amplifier discharge device having therein the voltage across said load and at least a portion of the voltage across said voltage stabilizing device in aiding relationship in said circuit, a second voltage stabilizing means to which current is sup.- plied from said auxiliary rectifying means to set up a substantially constant voltage thereacross, a current path connected across said second voltage stabilizingmeans comprising in series said f load and resistance means so that the voltage across said resistance means varies in response to the load with reode circuit of said regulator electronic device for controlling the anode-cathode resistance of said device in accordance with the output voltage of said amplier, said amplifier comprising a second electronic device having an anode, a cathode and a control electrode, a circuit connecting the anode and cathode of said second electronic device having therein a voltage larger thanthe load voltage for causing anode current to iiow in said circuit, and a circuit connecting .the control electrode and cathode of saidsecond electronic device having therein two opposed component voltages one of said component voltages Varying in accordance with load voltage changes and the other of said component cordance with load current changes.

11. Means for regulating the voltage across a load to which is supplied rectified alternating current from a source comprising electronic means having an input control grid-cathode circuit upon which a control voltage current iows for causing the amplitude of said tions of said control voltage, auxiliary rectifying means for producing an output voltage, voltage stabilizing means the resistance of which varies in response to current changes therethrough at a rate to cause the voltage across said vol-tage stabilizing means to remain substantially constant, and a current path connected in shunt with said load with respct to series the output oi said auxiliary rectifier, said voltage stabilizing means and a resistor, the output voltage of vsaid auxiliary rectifier being so related to said load voltage that the sum of the voltage drop across said voltage stabilizing means and the voltage drop across said resistor is greater than said load voltage, said input control gridcathode circuit including lsaid resistor for causing load voltage variations to be impressed upon said control grid-cathode circuit, thereby controlling the load current tov minimize load voltage variations.

JAMES A. PO'I'I'ER.

voltages'varying in ac- I is impressed and an out'- put anode-cathode circuit through which load said source comprising in. 

